The invention relates generally to high density propellant fuels, and more specifically, it relates to a new group of propellant fuels and fuel additives that use heterocyclic borane and carborane salt ingrediants.
Neutral borane and carborane compounds are known to be high energy compounds and have been considered for use in both formulated rocket propellant and explosives applications. Heterocyclic ionic solids and liquid salts, containing aromatic heterocyclic cations, are compounds that exhibit an almost non-existent vapor pressure and high ingredient densities.
Patented art of interest includes the following U.S. patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 4,855,508 entitled “Energetic diethers and process for their preparation” by Chapman, et al.
U.S. Pat. No. 4,424,398 entitled “Process for preparation of energetic plasticizers” by McGuire, et al.
U.S. Pat. No. 3,862,237 entitled “DIHYDROXY CARBORANES AND THE METHOD OF PREPARATION” by Knoeles.
U.S. Pat. No. 3,549,604 entitled “POLY-M-AND P-CARBORANYLENESULFIDES”.
U.S. Pat. No. 3,531,443 entitled “POLY-m AND p-CARBORANYLENEDISULFIDES”
The Chapman patent describes a preparation of energetically substituted diether compounds as energetic curatives and plasticizers for rocket propellant binders as well as stable solid oxidizers and industrial explosives.
The McGuire patent describes a process for synthesizing energetic ethers, esters and acetals useful as plasticizers, monomers or prepolymers for propellant binder systems.
The Knowles patent describes a use of 1,7- and 1,12-dihydroxy meta- and paracarboranes are prepared by the controlled oxidation of the corresponding di(alkali metal) carborane salts, used as burn rate modifiers for propellants, as polymer intermediates, and also in boron-neutron capture therapy and neutron radiation shields.
In U.S. Pat. No. 3,549,604 polycarboranylenesulfides are prepared by reacting 1,12-bis(halosulfenyl)-p-carborane with the dilithio salt of p-carborane in an inert solvent.
In U.S. Pat. No. 3,531,443 polycarboranylene disulfides consisting essentially of recurring units of the formula: _ES_M_S3_ wherein M is the meta or para carboranylene radical, are prepared by reacting absolute ethanol with a bis(halosulfenyl)-m-carborane or a bis(halosulfenyl)-p-carborane. These polymeric products are useful as high energy fuels when compounded with oxidizers.
While the above-cited references are instructive, combining both fuel-like borane and carboranes as anionic species into a salt with heterocyclic cationic species should produce very low vapor pressure fuels with a resultant significant energy and/or density increase, as described below. Uniqueness in this present invention comes from the composition of these salts being comprised of heterocyclic cations with carborane and/or borane anions. Such salt compositions are unknown in the chemical literature. Additional invention novelty would come from their unprecedented use as potential propellant fuels, fuel additives, or in fuel cell, gas generator and hydrogen storage applications.